Something to consider.
Current options for Foriegn Entry are easy, normal, hard & disabled. What about an 'always happens' or enabled option?
My rationale is that it would introduce an additional measure of replayability to the game for players. Having managed in my last two games to get the trigger to fire (once as either side) I found that it added a whole new dynamic to the game.
I appreciate that it's ahistorical but it does provide an enjoyable (and trickier) varient to the playing experience. As for the timing I guess it would have to be at some point before Lincoln's Emancipation Proclamation.